I'm pretty sure that frost occurs a few degrees above freezing. Thirty seven sticks in my brain, but don't take it to the bank. Of the plants you name, I have found geraniums (pelargoniums) to be somewhat more frost tolerant than the others. They actually bloomed all winter in New Orleans, and yes, we had light frost there occasionally. If your gernaiums are cranesbills, they should be winter hardy in the ground. Sweet potatoes will take a fair amount of cool weather too. I have actually had them return in my yard after a mild winter. That won't happen for you, of course, but we always do get freezes, sometimes down into the mid twenties. Why not just take some cuttings from the SPs and overwinter those? They'll be much less cumbersome. The fountain grass will take a bit of frost, but certainly not a freeze. The impatiens and hibiscus will tolerate little to none. Protect them first. (Some hibiscus are perennials. You'd need to check on the variety you have, and see if they're hardy in your zone.) I have no experience with Angel wings, but it seems that I remember they are perennials, so again, you'd want to check on their hardiness zone. It's sad shutting everything down for the year, isn't it? I have been sticking cuttings of things to overwinter in the basement all day and I'm already wishing for spring. :)

I'm on the 5/4 border and I just sowed 5 seeds from 8 different tomato varieties just to see what happens this early. Most of these varieties are Russian with short DTM, and I'm ready for tomatoes. I wondered if being Russian meant they might have a bit better cold tolerance. One of the 8 was also Brandywine. We'll see how they go! AFter they sprout I will protect them if we get a serious nighttime cold snap, though. The one annual I know I WON'T sow early is zinnias. Even if they survive, they won't grow worth a darn until the temps are decent. No sense in trying an early start with those. Still collecting the rest of my veggie seeds, and waiting to sow the rest of my annual seeds, as well as waiting on some annuals I just ordered.

I will start my tender annuals this week. Then when they sprout - mid-April - I feel fairly confident of little chance of frost. Altho if it does freeze (ugh - I hope not - I'm ready for HOT weather! :) I will do as others said, and cover. I once lost all my salvia to a late frost. Don't want that to happen.

Thank you both, that was after a day of beating myself up for being sooo stupid, I had indeed, early that evening ventured out to inspect "the troops" as I call them and came in telling hubby "gosh its parky (cold) out there", about an hour later I suddenly said oh no! I haven't covered the troops and I went out in my PJ's and it was sooo cold I ran in again and thought, they will be alright I've hardened them! even though I knew they where all heat loving plants! Bad, Bad, mummy! And I agree about the if we all cared about people as much as we care about plants...it would be a better place, I check my children in the morning then my plants, that said I wouldn't leave my kids uncovered, I hope I would run barefoot over coals for them! but don't test me on that! haha, but why do I feel so stupid? I can buy food! and the reason I agree is that unfortunatly there are people out there who have cottoned on to treating plants badly as well as people and you hit them all ways, Pol Pot, Mugarbe! "little bit of politic there" Ben Elton comedian UK well at least he was in the 80's and early 90's now he does Andrew Lloyd Webber Musicals....ahh! PS: I call them the Troops because that's what my Pop (Grandad) and Dad called them, and Ex Army both of them I think they where allowed to do that! haha, dad and grandad used to come in and say man down when a plant died....I can't believe I have only just remembered that this minute! actually thats good next post on dead plant should be army action film based???